Yesterday, I wrote about the Lady Beetle Larva. Once the larva reaches maximum size from chowing down aphids, it molts to the pupa stage. The pupa stage is intermediate between the larva and adult. However, you can clearly see where some of the adult features will form.

The pictures below are 3 angles of the same Lady Beetle Pupa. The first is taken from below. You can clearly see the round, black, compound eyes developing through the cuticle of the pupa. The pronotum (area behind the head) extends forward, protecting the head like a shield. A Lady Beetle Adult also has a pronotum that covers the head. You can barely see one of the legs that is forming.

The middle picture is a side view. You can see one compound eye and the head under the pronotum (to the left). The smooth shiny surface to the right of the head is the right wing pad, where one of the hard, shiny wings of the adult beetle is forming. The left wing pad on the other side. The cast skin of the larva is attached to the leaf. It is black and the spikes that were present on the larva can be clearly seen.

The picture to the right is a top view, mostly of the abdomen of the Lady Beetle. Once the adult emerges, the wings will expand, cover, protect and hide the top of the abdomen from view.

The cuticle of insects is made of proteins and a polysaccharide called chitin. When the adult cuticle is fully formed, digestive enzymes will be secreted that digest the portions of the pupa cuticle that are between the outside and the new adult cuticle that forms underneath. A line of weakness forms on the top of the cuticle of the pupa. The emerging adult will push against the pupa cuticle splitting it along the line of weakness, and a wrinkled adult will exit its old cuticle. Only after the adult emerges will the wings and cuticle fully expand and fully harden.

Lady Beetle Pupa

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About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010).
This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog.
The opinions and materials posted here are those of the author and are in no way connected with those of my employer.